Furnace door



Aug. 2, 1955 J. J. SEAVER 2,714,359

FURNACE DOOR Filed July 16, 1954 3 Sheets-Sheet 1L INVENTOR. JAY J. SEA VE/P Aug. 2, 1955 u. J. SEAVER FURNACE DOOR Filed July 16, 1954 3 Sheets-Sheet 2 Unit 2,714,359 Patented Aug. 2, 1955 FURNAGE DOOR Jay .3. Seaver, Evanston, Ill. Application July 16, 1954, Serial No. 443,818 14 (Iiaims. (Cl. Mil-176) This invention relates to furnace doors and is particularly concerned with an improved self-sealing door for open-hearth furnaces.

The door at the present time customarily used in openhearth furnaces comprises a panel-shaped slab of steel or cast iron forming a frame which is lined with fire brick and suspended from a chain or chains or the like, hanging practically loosely in front of the hearth opening. The brick lining is disposed on the inside of the door which faces the hearth and is held by the frame formed by the door panel. Access to the hearth is gained by lifting the chain or chains by a pulley mechanism to move the door upwardly so as to free the hearth opening. A door of this kind is shown on page 162, in The Open-Hearth Furnace, vol. I, William C. Buell, lr.; Penton Publishing Co., Cleveland, Ohio, 1936.

The above noted door has inherent disadvantages which affect the furnace operation and maintenance and also the safety of the operating personnel.

Flaming gases escape from the hearth opening around the edges of the loosely hanging door, causing loss of heat values and consequently inefiicient operation. Such escape of gases may have a detrimental effect on the control of the hearth in processing certain materials. The flaming gases escaping around the edges of the door cause warping of and consequent damage to the door frame which holds the brick lining and the chain mountings. This in turn loosens the brick lining and may damage the chain mountings and portions of the chains, requiring frequent repair and replacements and thus resulting in expenses and loss of operating time. The degree of damage suffered by such a door is cumulative and may be overlooked or underestimated by the operating personnel and the hearth may be started with a fatally defective door hanging. loosely in the manner of a curtain in front of the hearth opening. Parts or all of the brick lining of such defective door may crumble and tumble into the hearth after operation has been started and the door frame which is now wholly or partially unprotected is exposed to the full force of the hearth gases blasting against it on the inside and escaping around the edges thereof. Such a door and associated parts may be irreparably damaged under these circumstances; it is even possible that cumulative damage progresses to a point causing breakdown of the door during the hearth operation and consequently requiring interruption of the hearth operation prior to the completion of processing a run of material.

The chain or chains for raising and lowering the door are in prior structures under continuous stress which is particularly severe during the hearth operation when por tions of the. chains adjacent the door frame are subjected to the heat of the escaping hearth gases. Damage suffered by the chain mounting or by adjacent parts of the associated chain or chains may be overlooked or may be underestimated by the operating personnel, and such mounting or chain parts may crack and break during the operation of the hearth while the door hangs loosely in front of the hearth opening. The door which may weigh from a few hundred pounds up to two tons and even more, depending on the size of the hearth and its entry opening, might crash to the floor in such circumstance and endanger the operating personnel. If such breakage and consequent crashing down of the door should occur during the operation of the hearth, such operation must be interrupted. It may also happen that a minor explosion occurs in the hearth, during the processing of material,

causing sudden pressure forces against the loosely hanging door and consequently swinging or blowing the door away from the hearth opening with flaming gases bursting to the outside and endangering the operating personnel.

The object of the invention is to overcome the above noted and other disadvantages and drawbacks.

This object is realized by the provision of a door comprising a weight journalled on its frame for actuating a cam to wedge the door in its closed position in sealing engagement with the peripheral portions of the face of the hearth wall around the hearth opening, together with lifting means coacting with said weight and having during the opening of the door, that is, during its lifting, the dual function, namely, first, to release the door from its sealing engagement with the face of the hearth wall, and sec- 3 0nd, thereafter moving it upwardly to expose the hearth opening, and having during the closing of said door in reversed order the dual function of disposing the door looseiy in front of the hearth opening and thereafter releasing said weight so as to actuate the: cam for wedging the door in its closed position; and comprising guide and securing means having the triple function, namely, first, of guiding the door respectively into and out of its closed position, second, of cooperating with the wedging means to place the door in its closed position in sealing engagement with the peripheral portions of the hearth opening, and third, of securing and supporting the weight of the door in its closed sealing position in front of the hearth opening.

The guiding means provide a control over the movements of the door, thereby making the closing and opening operations more secure and safer. The sealing engagement of the door with the peripheral portions of the hearth opening prevents escape of hearth gases and blowouts of the door in the case of minor explosions occurring in the hearth, thereby contributing to more efficient material processing, protecting the door frame and associated parts against damage from flaming gases, and improving the safety of operation. The securing means which hold and support the weight of the door in its closed and sealed position in front of the hearth opening relieve strain on the chain or chains and their mountings, thereby eliminating stresses acting on these parts for extended periods of hearth operation and consequently prolonging the useful life thereof. The securing means in addition prevent crashing of the door to the floor, during the operation of the hearth, due to any cause, thus further contributing to safety and reliability of operation.

The above indicated and other objects and features will be brought out in the description of an embodiment of the invention which will presently be rendered with reference to the accompanying diagrammatic drawings. In these drawings,

Fig. 1 is an elevational front view of the new door in its closed position in front of the associated hearth opens;

Fig. 2 shows an elevational end view of the structure as seen when looking in the direction of the arrows along line 2-2 of Fig. 1;

Fig. 3 represents a portion of the door in section taken along line 33 of Fig. 1 to show one of the journals for the actuating mechanism;

Fig. 4 is a part sectional view through the door along line 4-4 of Pig. 1 to show the cam on the shaft and its cooperation with the door; and

Fig. 5 shows an elevational end view of the door similar to Fig. 2 but with the door in released and partly raised position.

Like parts are indicated by identical reference numerals throughout the drawings.

Numeral 11 indicates the hearth wall having the opening 12 and numeral 11 indicates a portion of the roof. The hearth wall as well as the roof may be of known structure comprising refractory material for example fire brick. Suitably mounted on the hearth wall 11 are pairs of guide and securing members 13/14 and 15/16, respectively. These guide and securing members are provided with downwardly and laterally inwardly sloping walls indicated at 13714 and 15716 forming a downward ly directed interrupted guideway for guiding the door panel 17 incident to its downward closing motion into the closed position in front of the hearth opening 12, in

which the door is shown in Figs. 1, 2, and 4. The door panel 17 is in some of the drawings cross-hatched as a metallic member for simplification only; it will be understood that the panel forms a frame made of suitable material such as cast iron, provided on the inside thereof with a suitable refractory lining, for example fire brick which is in suitable and known manner secured thereto.

On the front of the door panel 17 are disposed two bearing or journal brackets 18 and 19. These brackets are of identical structure, each comprising, as shown particularly in Fig. 3, a bifurcated body which is suitably mounted on the door panel. Within the space formed by the jaws of the member 18 is disposed a retainer plate 18' which is removably held by a bolt 13"; and within the space formed by the jaws of the member 19 is disposed a similar retainer plate 19 which is held in position by a similar bolt indicated at 19". The retainer plates or inserts 18 and 19' thus define in the corresponding members 18 and 19 bearing spaces for rotatably journalling the shaft 20 with some lateral or radial play, that is,

permitting a play for the shaft 20 perpendicularly toward and away from the face of the door panel 17.

The opposite ends of the shaft 20 project laterally beyond the edges of the door panel for disposal within the respective notches or recesses such as 21 (see Fig. 2)

formed in the guide and securing members 13 and 14. As will be seen particularly from Fig. 2, the recess 21 is limited outwardly by a prong 22 forming an upwardly and outwardly sloping guide wall 23 along which the corresponding end of the shaft 20 is guided into its terminal 1 position shown in Figs. 1 and 2. A similar recess is of course also formed in the guide and securing member 13 on the opposite edge of the door panel 17 (Fig.1), the prong 24 corresponding to the prong 22 of the member 14.

The shaft 20 carries a cam 25 which is suitably secured thereto and on the face of the door panel 17 is provided a boss 26. In the position in which the parts as shown in Figs. 1 to 4, that is, in the closed position in which the rear wall of the door 17 is in sealing engagement with peripheral portions of the face of the hearth wall, the rise of the cam 25 is in engagement with the boss 26. The cam accordingly exerts an outward pressure on the shaft attempting to move it perpendicularly away from the face of the door panel 17. The shaft 20 is thus slightly deflected outwardly throughout its central portion and is correspondingly moved forwardly, that is, outwardly within its bearing brackets 18 and 19, assuming a position within these brackets as indicated in Fig. 3. The opposite ends of the shaft 20 are limited in their outward displacement by the lower relatively steep portions of the sloping walls such as 23 (see Fig. 2) of the prongs 22 and 24 which terminate the corresponding recesses such as 21. The angularly outwardly and upwardly extending upper portions of these prongs operate as guides for i the shaft incident to the closing operation. The outer ends of the shaft 29 rest at the bottom of the recesses 21.

The resulting action is a wedging action, the cam 25 pressing against the boss 26 and thus holding the panel against the face of the hearth wall in sealing engagement therewith.

The rotation of the shaft 20 and therewith of the cam 25 into the actuated position shown in Figs. 1 to 4 is accomplished by the pressure of the weights 3% and 31 on the free ends 32, 33 of the levers 34, 35 which are keyed to the shaft at 36 and 37, respectively. Numerals 38, 39 indicate spacer bushings. The weights may be assembled of individual parts according to any given requirements and in large structures may represent a total weight of several hundred pounds.

The golds and securing members 15 and 16 extending from the face of the hearth wall 12 are recessed or bifurcated members (see also Fig. 2) each having a frontal prong forming an outwardly and upwardly sloping wall or guiding the pins 49 and 41 which are secured'to the sides of the door panel so as to direct the panel into its lowermost closed position. In such position, the pins are in wedging pressure engagement with the upwardly and outwardly sloping walls of the bifurcated members 15 and 16, thereby holding the lower portion of the door panel in pressure scaling engagement with the face of the hearth wall.

Accordingly, the door panel is held in its closed position with the opposite ends of the shaft 20 in engagement with the guide and securing members 13 and 14 and with the pins 4$41 resting on the upwardly and outwarcly sloping walls of the guide and securing members 1% and 16, and the door is thus in sealing engagement with the hearth wall and its Weight is supported partly by the members 23 and 14 and partly by the members 15 and 16. The chain 52 is shown prominently slackened in Fig. 2 for convenience of representation; it may be taken up in practical operation after the door panel is in its closed position.

The lifting and lowering mechanism comprises the brackets 45 and 46 carrying the idler rollers 47 and 48, respectively. Chains such as indicated in Fig. 2 at 50 extend from each of the weight-levers 34 and 35. The other ends of these chains are secured to the yoke 51 forming an equalizer from which extends a lifting chain 52 extending over a pulley 53 to the raising and lowering means 54. The latter may be suitably mounted, if desired on top of the hearth wall 11 as shown. Any desired and suitable raising and lowering drive mechanism 54 may be provided for the chain 52 so as to place the door in closed position in which it is shown in Fig. 14 or to raise it so as to gain access to the hearth through the opening 12.

The member 55 is a cover or lid which is rotatably journalled on the door panel 17 so as to cover or expose the sight opening 56 in the panel 17. Such sight opening is provided for observing the progress of the material-processing on the hearth and for taking measurements.

Certain aspects of the raising and lowering of the door will now be explained taking into consideration Fig. 5 in which the door is shown in partly raised position. The door will be in such position just after release incident to the raising thereof and will remain in such position until fully raised and also during the lowering just prior to reaching its closed position.

Considering first the raising of the door from its closed position explained with reference to Figs. 1 to 4: The chain 52 is pulled upwardly over the associated pulley 53, by the drive mechanism 54 and the equalizer 51 is accordingly lifted, exerting a pull on the chains 50 and thereby rotating the weight-levers 34 and 35 clockwise as viewed in Fig. 5 and thus into the position in which they and their associated weights are shown in Fig. 5. The weight-levers 34, 35 are in this manner initially rotated through a predetermined arc and at the end of such rotation abruptly engage the stops 60 formed by the brackets 45, 46. The shaft is coincidently rotated clockwise and rotates the cam accordingly to release the rise of the cam from engagement with the boss 26 on the face of the door panel 17, thus releasing the camming pressure on the shaft and thereby freeing the door for the raising operation. The door is somewhat jarred by the abrupt engagement of the lever arms 34, 35, with the stops 60 to aid in releasing it. Continued pull on the 1 chain 52 lifts the door; the opposite ends of the shaft 2% slide upwardly along the stepped sloping edges 23 of the recesses 21 in the guide and securing members 13 and 14 and the pins 40, 41 slide out of their recesses in the bottom guide and securing members 15, 16. The door frame or panel 17 is unbalanced due to the weight of the operating parts disposed on the upper portion thereof and such upper portion accordingly tilts and shifts outwardly away from the hearth wall 11 into the position shown in Fig. 5. Such position is retained until the door is fully raised. The hearth opening 12 is now freed and accessible as desired. The unbalanced condition of the door panel aids in freeing the panel from its sealing engagement with the furnace wall 11.

The closing operation proceeds in reversed order. The chain 52 is gradually released by the drive mechanism 54, moving downwardly with the door suspended there from in the forwardly inclined or tilted position shown in Fig. 5. Upon continued downward motion, the opposite ends of the shaft 20 will reach the prongs 22, 24 of the guiding and securing members 13 and 14 while the pins 40, 41 will be aimed directly in line with the upwardly and outwardly sloping walls of the retaining recesses in the securing, guiding and supporting members 15, 16 at the bottom of the structure. The opposite ends of the shaft 20 thereupon slide downwardly and inwardly along the sloping edges of the prongs 22, 24, thus moving the upper outwardly slanting or tilting portion of the door panel or frame similarly inwardly, toward the face of the hearth wall, until the ends of the shaft drop along the steep portions of the sloping prongs to the bottom of the corresponding recesses. The pins 40, 41 are at this time in inward pressure engagement with the sloping walls of the recesses in the members 15, 16. The vertical downward closing motion of the door is accordingly stopped. The door is now in the desired position in front of the hearth opening 12 and vertically aligned with the face of the hearth wall 11 as shown in Figs. 1, 2 and 4.

Further dropping of the chain 52 releases the lever arms 34, from engagement with the stops 6t) and these arms rotate counterclockwise by the pressure of the weights 30, 31 to rotate the shaft 20 and therewith the cam 25 so as to put the shaft under camming pressure which is as previously described effective for pressing the door into sealing engagement with the face of the hearth wall.

The invention is not inherently limited to open-hearth furnaces. Some or all features may be useful in other instances. Unless otherwise specified the term furnace" is accordingly intended to mean a furnace structure in which the invention may be used. Modifications are likewise possible. For example, the guide and securing members 13/14 and 15/16 are shown as integral members having surfaces 13/14' and 15/16 for guiding the door into closed position. These guide surfaces may obviously be formed by separate members. The guide and securing members 15/ 16 form stop means for limit ing the downward closing motion of the door and for holding and supporting it in closed position. Such stop means may be differently constructed, for example, in the form of a bracket or brackets extending from the face of the furnace wall and forming a channel or channels for receiving the bottom of the door. The prongs 22 and 24 of the guide and securing members 18 and 19 may ,to close such opening,

' pressure on said door be extended upwardly for a desired length so as to give additional security in the raising and lowering of the door. Chains have been shown and described for raising and lowering the door but equivalent means may of course be used.

It will be understood in view of the foregoing explanations that changes may be made within the scope and spirit of the appended claims.

I claim:

I. A door for use with a furnace having a wall enclosing a combustion space and having an opening formed in said wall for gaining access to said combustion space, said door comprising a panel, a shaft rotatably mounted on said panel in spaced relation to the front face thereof, the opposite ends of said shaft extending laterally beyond the corresponding edges of said panel, a cam on said shaft which is rotatable therewith, a lever arm rotatable with said shaft and angularly forwardly extending therefrom, a weight carried by said lever arm, operating means for disposing said panel in front of said furnace opening said weight exerting a force on said lever arm to rotate said shaft so as to rotate said cam into engagement with an area on the front face of said panel thereby tending to press said shaft outwardly away from said panel, and securing means extending forwardly from the face of said furnace wall for receiving the respective opposite ends of said shaft when said panel is disposed in front of said furnace opening and for holding said end against outward displacement away from said panel responsive to the pressure exerted on said shaft by the action of said cam for the purpose of utilizing said pressure to press said panel into sealing engagement with the peripheral portions of the face of said furnace wall defining the opening therein.

2. The structure defined in claim 1, comprising hearing means on either side of said cam for journalling said shaft for rotation therein and for radial play toward and away from the face of said panel.

3. The structure defined in claim 2, comprising means for holding the bottom portion of said door in sealing engagement with said furnace wall and for aiding in supporting its weight in the closed position thereof.

4. The structure defined in claim 3, wherein said operating means comprises a chain anchored at one end to said lever arm, and means for raising and lowering said chain, the raising of said chain causing initially rotation of said lever arm through a predetermined arc for the purpose of lifting said weight and coincidentally rotating said shaft to rotate said cam for releasing said sealing panel, stop means for engagement by said lever arm at the termination of rotation through said arc, the continued raising of said chain exerting a pull on said lever arm in engagement with said stop means to lift said door panel so as to gain access to said opening in said furnace wall, and the lowering of said chain causing initially lowering of said door panel from its lifted position to its closed position in front of said opening with said lever arm in engagement with said stop means, the continued lowering of said chain thereafter releasing said lever arm from engagement with said stop means to cause said weight to exert a force on said lever arm for rotating said shaft and coincidentally said cam to effect said sealing engagement of said door panel with the face of said furnace wall.

5. The structure defined in claim 3, comprising a pair of lever arms each carrying a weight and each keyed with said shaft for rotation therewith, said operating means comprising a first chain for each lever arm and anchored thereto at one end thereof, an equalizer yoke for receiving the other ends of said first chains in anchoring engagement therewith, second chain means anchored at one end to said equalizer yoke, and means for raising and lowering said second chain means, the raising of said second chain means exerting initially a pull on said first chains to rotate said lever arms through a predei termined are for the purpose of lifting the associated Weights and coincidentally rotating said shaft to rotate said cam for releasing said sealing pressure on said door panel, stop means for engagement by said lever arms at the termination of rotation thereof through said arc, the continued raising of said second chain means exerting a pull on said lever arms in engagement with said stop means to lift said door panel so as to gain access to said opening in said furnace wall, and the lowering of said second chain means causing initially lowering of said door panel from its lifted position to its closed position in front of said opening with said lever arms in engagement with said stop means, the continued lowering of said second chain means thereafter releasing said first chains to release said lever arms from engagement with said stop means so as to cause said weights to exert a force on said lever arms for rotating said shaft and coincidentally said cam to effect said sealing engagement of said door panel with the face of said furnace wall.

6. The structure defined in claim for guiding said door panel into its closed position in front of said opening in the furnace wall.

7. The structure defined in claim 5, comprising means integral with said securing means for guiding said door panel into its closed position in front of said opening in the furnace wall.

8. The structure defined in claim 5, wherein said means for holding said door panel and for supporting its weight in the closed position thereof comprises a holding member extending from said door panel, and a stop member extending from the face of said furnace wall for receiving said holding member.

9. The structure defined in claim 5, wherein said hearing means and said shaft and parts associated therewith are mounted on the face of said door panel near the top thereof, the weight of such elements and associated parts tending to unbalance the door panel and to exert a force thereon which causes the top portion of said door panel to tilt forwardly and outwardly relative to the face of said furnace wall after release of the sealing pressure of said cam incident to the initial raising of said second chain means, said tilting force aiding in the release of said door panel from its sealing engagement with the face of said furnace wall to facilitate the lifting of said door panel responsive to continued raising of said second chain means.

10. The structure defined in claim 9, wherein said door panel is maintained with its top portion forwardly and outwardly tilted while in raised position and during the lowering thereof into its closed position, and guide means on the face of said furnace wall for guiding said door panel into closed position in which it is disposed in parallel with the plane of the face of said furnace wall.

11. The structure defined in claim 10, wherein said guide means is integral with said securing means.

5, comprising means 12. The structure defined in claim 11, comprising second guide means for engagement by the opposite edges of said door panel to guide said panel into its closed position.

13. A door for use with a furnace having a wall enclosing a combustion chamber and having an opening formed in said wall for gaining access to said combustion chamoer, said door comprising a panel, and a device for releasably placing said door panel peripherally in sealing engagement with portions of said furnace wall surrounding said opening, said device including a first mechanism for holding the top portions of said panel in sealing engagement with said furnace wall, said first mechanism comprising a shaft rotatably mounted on said door panel near the top thereof, first retainer means mounted on said furnace wall for removably receiving the opposite ends of said shaft, a cam on said shaft which is rotatable therewith, a lever arm rotatable with said shaft and angularly forwardly extending therefrom, and a weight carried by said lever arm for exerting pressure thereon to rotate said shaft so as to rotate said cam for the purpose of exerting pressure on the top portion of said door panel to hold such top portion in sealing engagement with said furnace Wall by the reactive force exerted by the opposite ends of said shaft on said first retainer means, and a second mechanism for holding the bottom portions of said panel in sealing engagement with said furnace wall, said second mechanism comprising second retainer means extending from said furnace wall for releasably camming the bottom portions of said panel in sealing engagement with said furnace wall.

14. The structure and cooperation of parts as defined in claim 13, including a mechanism for raising said door panel, said last namedmechanism comprising an idler roller disposed on top of said door panel, first chain means secured at one end of said lever arm, a yoke for receiving the other end of said first chain means, second chain means extending from said yoke, means for exerting a pull on said second chain means so as to exert a force on said first chain means to rotate said lever arm for rotating said cam to release said reactive sealing pressure on said door panel, the weight of said first mechanism causing said panel to tilt forwardly out of sealing engagement with said furnace wall to facilitate release of the camming pressure exerted by said second mechanism responsive to further pulling force exerted on said second chain means.

References Cited in the file of this patent UNITED STATES PATENTS 1,529,272 Finder Mar. 10,1925 2,587,863 Lambert Mar. 4, 1952 2,600,441 Sommers et'al June 17, 1952 

